Conventional detergents used in warewashing include alkaline detergents. Alkaline detergents, particularly those intended for institutional use, in combination with the presence of hard water commonly result in heavy scale formation that is difficult to control, particularly in warewash applications at elevated temperatures. Alkaline detergents often contain polymers, phosphonates, and chelating agents such as nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) to help control scale, remove soils, and/or sequester metal ions such as calcium, magnesium, and iron.
Chelating agents and/or threshold agents are often used in high alkaline detergents because of their ability to solubilize metal salts and/or prevent calcium, magnesium, and iron salts from precipitating. When calcium, magnesium, and iron salts precipitate, the crystals may attached to the surface being cleaned and cause undesirable effects, such as spotting or films, which give the surface an unclean appearance.